Observational constraints on the nature of dark energy: First cosmological results from the essence supernova survey

W. M. Wood-Vasey, G. Miknaitis, C. W. Stubbs, S. Jha, A. G. Riess, P. M. Garnavich, R. P. Kirshner, C. Aguilera, A. C. Becker, J. W. Blackman, S. Blondin, P. Challis, A. Clocchiatti, A. Conley, R. Covarrubias, T. M. Davis, A. V. Filippenko, R. J. Foley, A. Garg, M. HickenK. Krisciunas, B. Leibundgut, W. Li, T. Matheson, A. Miceli, G. Narayan, G. Pignata, J. L. Prieto, A. Rest, M. E. Salvo, B. P. Schmidt, R. C. Smith, J. Sollerman, J. Spyromilio, J. L. Tonry, N. B. Suntzeff, A. Zenteno

Research output: Contribution to journalArticlepeer-review


We present constraints on the dark energy equation-of-state parameter, w = P/(pc2), using 60 SNe Ia from the ESSENCE supernova survey. We derive a set of constraints on the nature of the dark energy assuming a flat universe. By including constraints on (ΩM, w) from baryon acoustic oscillations, we obtain a value for a static equation-of-state parameter w = -1.05+0.13-0.12 (stat 1 σ)±0.13 (sys) and ΩM= 0.274-0.020+0.033 (stat 1σ ) with a bestfit x2/dof of 0.96. These results are consistent with those reported by the Supernova Legacy Survey from the first year of a similar program measuring supernova distances and redshifts. We evaluate sources of systematic error that afflict supernova observations and present Monte Carlo simulations that explore these effects. Currently, the largest systematic with the potential to affect our measurements is the treatment of extinction due to dust in the supernova host galaxies. Combining our set of ESSENCE SNe Ia with the first-results Supernova Legacy Survey SNe Ia, we obtain a joint constraint of w = -1.07-0.09+0.09(stat 1 σ) ±0.13 (sys), ΩM = 0.267-0.018+0.028 (stat 1 σ) with a best-fit x2/dof of 0.91. The current global SN Ia data alone rule out empty (ΩM = 0), matter-only ΩM = 0.3, and ΩM = 1 universes at >4.5 σ. The current SN Ia data are fully consistent with a cosmological constant.

Original languageEnglish (US)
Pages (from-to)694-715
Number of pages22
JournalAstrophysical Journal
Issue number2 I
StatePublished - 2007
Externally publishedYes


  • Cosmological parameters
  • Cosmology: observations
  • Supernovae: general

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


Dive into the research topics of 'Observational constraints on the nature of dark energy: First cosmological results from the essence supernova survey'. Together they form a unique fingerprint.

Cite this